Endothelin-1 Induced Middle Cerebral Artery Occlusion Model for Ischemic Stroke with Laser Doppler Flowmetry Guidance in Rat

Stroke is the number one cause of disability and third leading cause of death in the world, costing an estimated $70 billion in the United States in 2009^{1, 2}. Several models of cerebral ischemia have been developed to mimic the human condition of stroke. It has been suggested that up to 80% of all strokes result from ischemic damage in the middle cerebral artery (MCA) area³. In the early 1990s, endothelin-1 (ET-1) ⁴ was used to induce ischemia by applying it directly adjacent to the surface of the MCA after craniotomy. Later, this model was modified ⁵ by using a stereotaxic injection of ET-1 adjacent to the MCA to produce focal cerebral ischemia. The main advantages of this model include the ability to perform the procedure quickly, the ability to control artery constriction by altering the dose of ET-1 delivered, no need to manipulate the extracranial vessels supplying blood to the brain as well as gradual reperfusion rates that more closely mimics the reperfusion in humans^5-7. On the other hand, the ET-1 model has disadvantages that include the need for a craniotomy, as well as higher variability in stroke volume⁸. This variability can be reduced with the use of laser Doppler flowmetry (LDF) to verify cerebral ischemia during ET-1 infusion. Factors that affect stroke variability include precision of infusion and the batch of the ET-1 used⁶. Another important consideration is that although reperfusion is a common occurrence in human stroke, the duration of occlusion for ET-1 induced MCAO may not closely mimic that of human stroke where many patients have partial reperfusion over a period of hours to days following occlusion^{9, 10}. This protocol will describe in detail the ET-1 induced MCAO model for ischemic stroke in rats. It will also draw attention to special considerations and potential drawbacks throughout the procedure.     

Adherence to Antihypertensive Therapy and Elevated Blood Pressure: Should We Consider the Use of Multiple Medications?

Background

Although a majority of patients with hypertension require a multidrug therapy, this is rarely considered when measuring adherence from refill data. Moreover, investigating the association between refill non-adherence to antihypertensive therapy (AHT) and elevated blood pressure (BP) has been advocated.

Objective

Identify factors associated with non-adherence to AHT, considering the multidrug therapy, and investigate the association between non-adherence to AHT and elevated BP.

Methods

A retrospective cohort study including patients with hypertension, identified from a random sample of 5025 Swedish adults. Two measures of adherence were estimated by the proportion of days covered method (PDC≥80%): (1) Adherence to any antihypertensive medication and, (2) adherence to the full AHT regimen. Multiple logistic regressions were performed to investigate the association between sociodemographic factors (age, sex, education, income), clinical factors (user profile, number of antihypertensive medications, healthcare use, cardiovascular comorbidities) and non-adherence. Moreover, the association between non-adherence (long-term and a month prior to BP measurement) and elevated BP was investigated.

Results

Non-adherence to any antihypertensive medication was higher among persons < 65 years (Odds Ratio, OR 2.75 [95% CI, 1.18–6.43]) and with the lowest income (OR 2.05 [95% CI, 1.01–4.16]). Non-adherence to the full AHT regimen was higher among new users (OR 2.04 [95% CI, 1.32–3.15]), persons using specialized healthcare (OR 1.63, [95% CI, 1.14–2.32]), and having multiple antihypertensive medications (OR 1.85 [95% CI, 1.25–2.75] and OR 5.22 [95% CI, 3.48–7.83], for 2 and ≥3 antihypertensive medications, respectively). Non-adherence to any antihypertensive medication a month prior to healthcare visit was associated with elevated BP.

Conclusion

Sociodemographic factors were associated with non-adherence to any antihypertensive medication while clinical factors with non-adherence to the full AHT regimen. These differing findings support considering the use of multiple antihypertensive medications when measuring refill adherence. Monitoring patients'' refill adherence prior to healthcare visit may facilitate interpreting elevated BP.     

Selection of orlistat as a potential inhibitor for lipase from Candida species

Infections caused by Candida species manifest in a number of diseases, including candidemia, vulvovaginal candidiasis, endocarditis, and peritonitis. Candida species have been reported to possess lipolytic activity due to the secretion of lipolytic enzymes such as esterases, lipases and phospholipases. Extra-cellular hydrolytic enzymes seem to play an important role in Candida overgrowth. Candidiasis is commonly treated with antimycotics such as clotrimazole and nystatin. The antimycotics bind to a major component of the fungal cell membrane (ergosterol), forming pores that lead to death of the fungus. However, the secondary effects caused during such treatment have aroused a need to develop a treatment based on lipase inhibition. Nonetheless, no such lipase inhibitors for candidiasis treatment are currently available. Thus, we have performed a docking study with the natural inhibitor, orlistat or tetrahydrolipstatin. Our results have shown ten possible binding inhibitors to Candida rugosa lipase (CRL), out of which one possibility was selected, based on the weakest interatomic distance of 2.7 ?. Therefore, we propose the selection and design of a potential inhibitor candidate, orlistat for the treatment of candidiasis infections. However, this study has to be supported with in vitro and in vivo experiments to demonstrate the effectiveness of orlistat in lipase inhibition.     

Percentage of patients with preventable adverse drug reactions and preventability of adverse drug reactions--a meta-analysis

Background

Numerous observational studies suggest that preventable adverse drug reactions are a significant burden in healthcare, but no meta-analysis using a standardised definition for adverse drug reactions exists. The aim of the study was to estimate the percentage of patients with preventable adverse drug reactions and the preventability of adverse drug reactions in adult outpatients and inpatients.

Methods

Studies were identified through searching Cochrane, CINAHL, EMBASE, IPA, Medline, PsycINFO and Web of Science in September 2010, and by hand searching the reference lists of identified papers. Original peer-reviewed research articles in English that defined adverse drug reactions according to WHO’s or similar definition and assessed preventability were included. Disease or treatment specific studies were excluded. Meta-analysis on the percentage of patients with preventable adverse drug reactions and the preventability of adverse drug reactions was conducted.

Results

Data were analysed from 16 original studies on outpatients with 48797 emergency visits or hospital admissions and from 8 studies involving 24128 inpatients. No studies in primary care were identified. Among adult outpatients, 2.0% (95% confidence interval (CI): 1.2–3.2%) had preventable adverse drug reactions and 52% (95% CI: 42–62%) of adverse drug reactions were preventable. Among inpatients, 1.6% (95% CI: 0.1–51%) had preventable adverse drug reactions and 45% (95% CI: 33–58%) of adverse drug reactions were preventable.

Conclusions

This meta-analysis corroborates that preventable adverse drug reactions are a significant burden to healthcare among adult outpatients. Among both outpatients and inpatients, approximately half of adverse drug reactions are preventable, demonstrating that further evidence on prevention strategies is required. The percentage of patients with preventable adverse drug reactions among inpatients and in primary care is largely unknown and should be investigated in future research.     

Isolation and characterization of an Arabidopsis thaliana knockout line for phospholipid: diacylglycerol transacylase gene (At5g13640).

To more fully understand the function of phospholipid: diacylglycerol acyltransferase (PDAT, EC 2.3.1.158) in plants we have isolated and characterized a knockout mutant of Arabidopsis thaliana L. which has a T-DNA insertion in PDAT locus At5g13640. Lipid analysis was conducted on these plants to assess the contribution of the PDAT gene to lipid composition. The fatty acid content and composition in seeds do not show significant changes in the mutant. This is a contrary situation to yeast where PDAT is a major contributor to triacylglycerol (TAG) accumulation in exponential growth phase. The results indicate that PDAT activity encoded by At5g13640 is not a major determinant of TAG synthesis in Arabidopsis seeds.